1. Field of the Invention
The present invention relates to an encoding/decoding system, an encoding system, and a decoding system, an encoding/decoding method, an encoding method, and a decoding method, and a computer product.
2. Description of the Related Art
With the beginning of terrestrial digital broadcasting, a moving-picture encoding system that encodes a high-resolution moving-picture signal of a high definition television (HDTV) class (hereinafter, “encoding system”) and a motion-picture decoding system that decodes encoded data to reproduce the original moving-picture signal (hereinafter, “decoding system”) have been needed to be popularized. In the future, an encoding system and a decoding system that can handle high-resolution moving-picture signals of an ultra definition television (UDTV) class will be demanded.
Because the encoding system and the decoding system that handle high-resolution moving-picture signals need high-performance and large-scale resources (such as hardware and software), realization thereof is not easy. Furthermore, even if these systems can be realized, these systems will have to be expensive. Therefore, a handling method of high-resolution moving-picture signals has been proposed, which divides a high-resolution moving-picture signal into a plurality of low-resolution moving-picture signals, and encodes the divided low-resolution moving-picture signals by a low-performance encoding system, or decodes the encoded moving-picture signals by a low-performance decoding system.
For example, in the method disclosed in Japanese Patent Application Laid-Open No. 2001-346201, in an “encoding system”, a high-resolution moving-picture signal is divided into a plurality of low-resolution moving-picture signals, the divided low-resolution moving-picture signals are respectively encoded by a plurality of encoders, and the encoded data is integrated in one system stream and transmitted to a “decoding system”. In the “decoding system”, a plurality of pieces of encoded data are separated from the transmitted one system stream, the separated data is respectively decoded by a plurality of decoders to reproduce a plurality of low-resolution moving-picture signals, and the reproduced low-resolution moving-picture signals are integrated to display the high-resolution moving-picture signal.
In the conventional technique, as explained below, synchronization of a display time cannot be achieved, and therefore the high-resolution moving-picture signal cannot be correctly displayed. That is, in encoding and decoding of the moving-picture signals, the time when the moving-picture signal has been captured by the encoder is generally reproduced as a “display time” by the decoder, and the moving-picture signal is output to an output unit at the “display time”. However, with the method disclosed in Japanese Patent Application Laid-Open No. 2001-346201, for example, when a plurality of encoders are used, the time generally deviates from each other between clocks built in the respective encoders. As a result, on the decoder side, synchronization of the “display time” cannot be achieved between the encoded data, and therefore the high-resolution moving-picture signal cannot be displayed correctly.